When you speak with the courier, after you get the mail and the dialogue is complete, if you drop armor in front of him, he will ask you if he can have it. You get two choices; Yes or no (with more words than just that). After you say yes, he picks it up and puts it on. Freaking awesome. You can dress the courier LMFAO.
This happened after I had finished escaping the prison mines and he told me about the new museum opening up. I'm not sure if it's specific or if it happens whenever but I thought I would bring that to light. If it's already been found, disregard this message and carry on. XD